Design and analysis of lunar lander control system architectures

Abstract

Although a great deal of separate work exists on the development of spacecraft actuators and control algorithm design, less work exists which examines the connections between the selection of specific actuator types and placements, how this affects control algorithm design, and how these combined factors affect the overall vehicle performance of a lunar lander. This thesis attempts to address these issues by combining a functionality-oriented approach to actuator type/placement with a controls-oriented approach to algorithm design and performance analysis. Three example control system architectures are examined for a generic autonomous 350kg lunar lander during the terminal descent flight phase. Results indicate that stability and control can be achieved using a wide variety of actuator types/placements and algorithms given that a set of 'common sense' subsystem functionality and robustness metrics are met; however, algorithm development was often heavily influenced/restricted by actuator system capabilities. It is therefore recommended that future designers of lunar lander vehicles consider the impact of their control system architectures from both a functionality-oriented and a controls-oriented approach to gain a more complete understanding of the effects of their choices on overall performance.